Paper bail structure for typewriters and the like



T. TOEPPEN Sept. 5, 1967 PAPER BAIL STRUCTURE FOR TYPEWRITERS AND THELIKE 5 sfieets-sheet 1 Filed July 12, 1965 INVENTOR. THURSTON H. TOEPPENATTORNEY T. H. TOEPPEN Sept. 5, 1967 PAPER BAIL STRUCTURE FORTYPEWRITBRS AND THE LIKE Filed July 12, 1965 I: Sheets-Sheet 2 INVENTOR-THURSTON H. TOEPPEN BY 2% ig ATTORNEY Sept. 5, 1967 T. H. TOEPPEN3,339,696

PAPER BAIL STRUCTURE FOR TYPEWRITERS AND THE LIKE Filed July 12, 1965' 3Sheets-Sheet 5 INVENT THURSTON H.TOE N ATTORNEY United States Patent3,339,696 PAPER BAIL STRUCTURE FOR TYPEWRITERS AND THE LIKE Thurston H.Toeppen, Poughkeepsie, N.Y., assignor to Friden, Inc., Rochester, N .Y.,a corporation of Delaware Filed July 12, 1965, Ser. No. 471,087 4Claims. (Cl. 197-138) This invention relates to paper bails fortypewriters.

It is to be understood that the term typewriters as used herein includesconventional typewriters and other forms of oflice and business machinesfor imprinting characters of a work sheet of paper or the like, whereinthe work sheet to be printed is guided around a platen into the printingposition. A typewriter as thus defined is usually provided with a paperbail arranged to press the work sheet firmly against the platen at alocality above the printing line and thereby, in cooperation with otherstructures below the printing line, to maintain the work sheet in smoothcontinuous engagement with the platen at the point where it is struck bythe type. The paper bail structure ordinarily includes a bar extendingin a direction parallel to the platen axis and bearing a plurality ofrotatable rollers for engaging the Work sheet. To facilitate feeding ofthe work sheet into the machine, and also to afford convenient access tothe work sheet at the printing line for the purpose of making erasuresor corrections, the paper bail is desirably movable between itsplaten-engaging or operating position and one or more other positions inwhich the bar and rollers are spaced away from the work sheet.

In some known forms of paper bail structures, the roller-carrying bar issupported by a pair of plain, pivoted arms arranged to swing the bailbetween its operating position and a clearance position in which thebail is disposed above and rearwardly of the platen, spring pressuresbeing applied to the arms to hold the bail in either of these positions.Such bail structures are simple in construction and operation butprovide only a single motion path between the two positions, so that inreturning from the clearance to the operating position the bailnecessarily approaches the platen and work sheet in a downward directionand as a result oft-en tends to cause buckling of the work sheet at theprinting line.

To obviate this difficulty, in other forms of paper bails as heretoforeused different or alternative clearance positions have been provided,usually by means of some articulated arrangement of the bail-supportingarms. In particular, these so-called multiposition paper bails commonlyprovide an additional forward clearance position in which the bail issuspended ahead of and in spaced relation to the platen. From the latterclearance position, the bail returns to the platen along a rearwardlydirected path, rather than a downwardly directed path; the rearwarddirection of motion tends to smooth the work sheet rather than to buckleit as the bail engages the paper. Multiposition paper bails are alsoadvantageous in providing some option as to the motion path followed bythe bail, to accommodate the convenience and preference of the operator.Thus, a typical multiposition bail may be moved from operating positionto the normal clearance position (above and behind the platen) and backeither along a direct path as in the case of a simple two-position bailor along an alternate path through the aforementioned forward clearanceposition.

However, multiposition paper bails as previously known tend to bestructurally complex and also very commonly do not afford the desiredsmoothness of operation, owing in particular to the multiplicity ofspring biasing, detent forces, and guiding surfaces that must beprovided to maintain the bail in each of the desired plurality ofpositions. For example, as the bail is moved from normal clearanceposition to the forward clearance position or to operating position itmay tend to jump between the alternate paths provided; again, movementof the bail from the forward clearance position to the operatingposition may be accompanied by an undesirable snapping or jerkingmotion.

An object of the present invention is to provide a new and improved formof multiposition paper bail of advantageously simplified construction.

A further object is to provide such multiposition paper bail, affordinga selection of motion paths between clearance position and operatingposition, which is particularly arranged to enable the bail to approachthe platen in an upward and rearward direction so as to prevent bucklingof the work sheet and indeed to provide positive smoothing action forassured firm, continuous engagement of the work sheet with the platen.

Further objects and advantages of the invention will be apparent fromthe detailed description hereinbelow set forth, together with theaccompanying drawings, wherein:

FIG. 1 is an elevational view of the right-hand end of a typewritercarriage which includes a paper bail structure embodying the presentinvention in aparticular form;

FIG. 2 is a diagram illustrating the positions and motion paths ofmultiposition paper bail structures as viewed from the right-hand end ofa typewriter carriage, for reference in explaining the arrangement andoperation of the paper bail of the present invention;

FIG. 3 is a somewhat simplified elevational view of the right-hand endof the paper bail structure of FIG. 1 in operating position;

FIG. 4 is a like view of the paper bail structure of FIG. 1 in clearanceposition; and

FIG. 5 is a like view of the paper bail structure of FIG. 1 illustratingone mode of return of the hail from clearance position to operatingposition.

Referring first to FIG. 1, there is shown in right-hand end view atypewriter carriage 10 including a right-hand side plate 11 which issecured in spaced parallel relation to a left-hand side plate (notshown) by frame structure including tie rods 12, 14 to provide a rigidcarriage frame. The tie rods are received in slots 17, 18 of side plate11 and are held in place by hexagonal nuts 19, 20. The car riage framealso includes a channel-shaped member 21 extending between and rigidlysecured to the side plates; member 21 has sides formed as grooves 23, 24to retain bearings 25, 26 by means of which the carriage is mounted onguide rails 27, 28 of the typewriter base frame 29 for transversemovement relative to the base frame in typing operation.

A cylindrical platen 30 of rubber or the like, extending between thecarriage side plates, is rotatably mounted in the carriage by meansindicated at 31. A sloping paper table 33 is disposed in the carriagebehind the platen to facilitate feeding of paper into the machine fromthe rear of the platen. To guide the paper beneath the platen, there isprovided a curved paper deflecting plate 34 positioned immediately belowthe platen. A further guide member 35, also mounted in the carriage withan edge 36 disposed in closely proximate relation to the platen at alocality above and ahead of the leading edge of deflecting plate 34,directs the paper upwardly around the front of the platen into theprinting locality 37 where the paper is struck by the type, and pressesthe paper closely against the platen immediately below the printinglocality.

It will be appreciated that the illustrated carriage frame and platenare generally conventional structures and function in the known mannerof such devices in typing operation. Thus the work sheet to be printedis fed downwardly at the rear of the platen and advanced forwardly andupwardly around the platen into typing position by rotational movementof the platen in a clockwise direction as seen in FIG. 1. Thereafter astyping proceeds the paper is successively advanced upwardly past thetyping line by further clockwise rotation of the platen.

As incorporated in the carriage 10, the paper bail structure of thepresent invention is adapted to press the paper against the platen at alocality above the printing position 37, thereby (in cooperation withguide member 35) to hold the paper in smooth continuous engagement withthe platen at such printing locality, the bail structure further beingmovable away from its operating or platen-engaging position for ease ofaccess to the paper at the typing line and to facilitate feeding ofpaper to the machine.

The bail structure, in its illustrated embodiment, includes a torqueshaft 38 journalled for rotation about its axis in the carriage framerearwardly of the platen and in axially parallel relation to the platen.A torque arm 40 is fixedly secured at its lower end to shaft 38 adjacentto the right-hand end of the platen for rotational movement with thelatter shaft and extends generally upward therefrom; a correspondingtorque arm (not shown) is secured in the same manner to the torque shaftadjacent the lefthand end of the platen. These two torque arms are thuspivotally movable about the torque shaft axis, forwardly and rearwardlyrelative to the platen in parallel planes of rotation perpendicular tothe platen axis, being kept in phase with each other during suchmovement by the torque shaft to which they are secured.

A bail arm 42 is secured to the upper end of torque arm 40 by means of apivot 43 and extends forwardly from this pivot in transverse relation tothe platen axis; a second and corresponding bail arm (not shown) ismounted in like manner to the left-hand torque arm referred to above.Secured to and extending between the forward ends of the bail arms, inaxially parallel relation to the platen, is a bail member comprising arod 45 bearing a plurality of rotatable rollers 46. The joints betweenthe bail arms 42 and rod 45 are loose to allow the bail to adapt itselfaccurately to the platen. As will be apparent, angular displacement ofthe bail arms about the pivots connecting them to the torque armscarries the bail member into and away from a position in which therollers 46 engage the platen 30 for holding the work sheet in theaforementioned manner. This angular displacement of the bail anms isgenerally upward and downward relative to the torque arms and platen,the bail arms moving in parallel planes of rotation perpendicular to theplaten axis.

Torque arm 40 has an arcuate lot 48 extending forwardly and rearwardly(that is, in the direction of pivotal movement of the torque arm beinglimited by engagement torque shaft 38 and pivot 43. Tie rod 14 of thecarriage frame structure extends through the slot 48 and acts as a stopfor the torque arm, forward and rearward pivotal movement of the torquearm being limited by engagement of rod 14 with the rearward end 49 andforward end 50, respectively, of slot 48. The tie rod 14 also extendsthrough a similar slot (not shown) prOVided in the lefthand torque armof the bail structure. Bail arm 42 (as likewise the correspondingleft-hand bail arm) bears a finger-like projection 52 extendingrearwardly from pivot 43; this projection 52 swings down as the bail arm42 is rotated upwardly and rearwardly from the operating position shownin FIG. 1, so that when the bail arm is in a generally upward positionthe said projection, and that on the left-hand bail arm, engage tie rod14 to arrest further upward rotation of the bail arms.

The bail structure of the invention further include a torsion spring 54having a lower arm 55 which bears against a pin 56 secured to theright-hand carriag frame plate 11 at a locality below bail arm 42, andan upper arm 58 which bears against a pin 59 secured to and carried bybail arm 42 in adjacent but eccentric relation to pivot 43. Spring 54 isin a state of continuous compression between pins 56 and 59 and thusexerts outward forces against these pins in a generally vertical planetransverse to the platen axis. As shown, spring 54 open rearwardly andupwardly from pin 56 so that the force it exerts against pin 59 has atall times a net rearward component.

The bail structure thus provided is a multiposition paper bail in whichthe bail member may be moved betweeen the operating position of FIG. 1and a plurality of other positions along a variety of motion paths atthe option of the operator. In such multiposition paper bails, theprovision of torque arms carried by a torque shaft for inphase pivotalmovement relative to the carriage frame, and bail arms pivoted to thetorque arms for carrying the paper bail member, is broadly conventional,the particular features of the present invention residing in thearrangements of spring biasing means and stop means herein provided. Foran understanding of the arrangement and operation of the spring forcesand stop locations in the present bail structure, reference may be madeto FIG. 2 which illustrates diagrammatically the various motion pathsand detent positions provided in conventional multiposition paper bails.

These positions and motion paths are determined by the pivotal movementof the torque arms relative to the carriage frame and of the bail armsrelative to the torque arms. In FIG. 2, line 60 represents the forwardlimiting position of torque arm movement relative to the carriage frameand line 61 represents the rearward limiting position of torque armmovement; 62 represents the downward limiting position of bail armmovement relative to the torque arm and 63 represents the upwardlimiting position of bail arm movement, as found in a conventionalmultiposition paper bail. The combination of downward and upwardlimiting positions of the bail arms and rearward and forward limitingpositions of the torque arms provides four possible stop or detentlocations as indicated, at I, II, III and IV in FIG. 2. Of these, thethree positions commonly utilized in multiposition paper bails are theoperating position (I), normal or rearward clearance position (II), andforward clearance position (III). In the operating position (I), inwhich the bail rollers engage platen 30, the torque arms are at theirrearward limiting position and the bail arms are at their downwardlimiting position. From position I the bail may be moved to the normalclearance position (II), wherein the bail is disposed upwardly andrearwardly of the platen, by rotation of the bail arms to their upwardlimit 63 while the torque arms remain at their rearward limit 61. Toreach the forward clearance position (III), in which the bail issuspended ahead of and in spaced relation to the platen, the torque armis moved to its forward limit 60 and the bail arm to its downward limit62 passing through an intermediate position (IV) wherein the torque armis at its forward limit 60 and the bail arm at its upward limit 63.Movement of the bail between these several positions can occur through avariety of paths, one such path being indicated between positions I andII in FIG. 2 and another being indicated between positions II and IIIpassing through position IV, with the bail returning to position I fromposition III.

Referring again to the paper bail structure of FIG. 1, in FIG. 3 thisbail is shown in the operating position I in which the rollers 46 engageplaten 30. In this position, torque arm 40 is at the rearward limit ofits pivotal path, tie rod 14 engaging the forward end 50 of slot 48 toarrest torque arm 40 against further rearward displacement. Bail arm 42is in a downward position relative to torque arm 40, being restrainedagainst further downward rotation by the engagement of rollers 46 withplaten 30.

When the bail is in the operating position, the eccentric pin 59 carriedby bail arm 42 is disposed generally below pin 43, so that the torsionspring 54 (which exerts a net rearward component of force on pin 59)urges or biases bail arm 42 downwardly (that is, for counterclockwiserotation about pivot 43 as seen in FIG. 3), so as to hold the rollers 46in maintained engagement with platen 30. The rearward force exerted :byspring 54 against pin 59 is also transmitted through the bail arm 42 andpivot 43 to the torque arm 40; this force biases torque arm 40rearwardly (for clockwise rotation as seen in FIG. 3) so as to press theforward end 50 of slot 48 against tie rod 14 and thereby to maintaintorque arm 40 in its rearward limiting position.

The bail is moved from the operating position to the normal clearanceposition II, in which the bail member is disposed upwardly andrearwardly of the platen, by manual clockwise rotation of the bail andbail arms relative to the torque arms. This rotation continues, carryingthe bail member upwardly away from the platen, until projection 52 ofbail arm 42 swings downwardly and forwardly to engage the tie rod 14 andthus to arrest further upward rotation of the bail, as shown in FIG. 4.Such rotation of the bail arm carries pin 59 around to a position inwhich it is above and ahead of pivot 43; as a result, when the bailreaches position 11 the force of spring 54 on pin 59 biases the bail arm42 for upward or clockwise rotation. That is to say, in this clearanceposition the bail arm is biased in a direction opposite to that providedwhen the bail arm is in operating position so that projection 52 isforced against the tie rod 14 to hold the bail in the clearanceposition. However, the force of the spring on pin 59 as transmitted totorque arm 40 through pivot 43 still biases torque arm 40 for rearwardor clockwise rotation and thereby maintains the torque art at itsrearward limiting position with the forward end 50 of slot 48 engagingthe tie rod 14.

It will be appreciated that positions I and II of the present paper bailstructure as described above correspond respectively to thelike-designated positions of conventional multiposition paper bailsshown in FIG. 2, the spring biasing forces and stop arrangements of thestructure cooperating to retain the bail in each of these positions whenthe bail is moved thereto.

From position II the bail structure of the invention may be returned tothe operating position I through a variety of motion paths at the choiceof the operator. By lowering the bail with a slight pressure to therear, the operator can return it directly to position I along the pathindi cated at 65 in FIG. 4. If, however, the bail is lowered with aslight pull to the front, torque arm 40 will swing forward and the bailwill follow the path indicated at 66 in FIG. 4. Since projection 52 ofthe bail arm 42 engages tie rod 14 in position II, it will be apparentthat as the bail is moved along the path 66 forward rotation of torquearm 40 is limited by the gradual retraction of projection 52 relative totie rod 14 until the latter projection swings entirely clear of the tierod; this gradual retraction assures a smooth transition of torque arm40' to its forward position.

If the outer path 66 is followed to its lowest point, the bail reaches aposition designated Illa in which the rollers 46 engage the platen 30but at a locality ahead of and below the locality of engagement when thebail is in operating position I. As the bail approaches position IIIapin 59 again moves to a location (relative to pivot 43) in which theforce of spring 54 urges bail arm 42 downwardly or counterclockwise asseen in FIG. 5, thus forcing the rollers against the platen 30. Inposition 1111:, the torque arm 40 is at its forward limiting position atwhich tie rod 14 engages the rear end 49 of slot 48. However, the forceof spring 54 transmitted through pivot 43 still biases torque arm 40 forclockwise rotation, urging the torque arm toward its rearward limitingposition, so that the bail tends to return to the operating position Iunless restrained by the operator.

That is to say, in the present bail structure the conventional detentedforward clearance position (III in Fig. 2) is eliminated, the bailrollers being engageable with the platen (by downward pivotal movementof the bail arms) at all positions of the torque arms rather than onlynear the rearward position of the torque arms as in conventionalstructures, so that the forward-and-downward limit of bail movement isthe described position 1114:; as there is no detent or stop of the bailat a forward clearance position, the bail moves smoothly andcontinuously down from its rearward clearance position into contact withthe platen as at position Illa. In practice the operator will notordinarily pull the bail down all the way to position IIIa, since thepurpose in following this path of return to the operating position issimply to enable the bail to approach the operating position along anupward and rearward path effective to smooth the paper against theplaten. Thus, the bail may initially engage the platen at a localityintermediate positions 111:; and I and may then be permitted to movesmoothly up to position I, in response to the described spring forces,by gradual release of the bail.

It Will now be appreciated that in the operation of the paper bailstructure of the invention, the bias applied to the torque arm 40 isalways rearward (clockwise) while the bias applied to the bail arm 42 isdownward or upward (counterclockwise or clockwise) depending on whetherthe bail member is in platen-engaging position or in its upward,clearance position, for maintaining the bail arms in either of thesepositions. These various bias directions, provided by application of asingle force to a single point on the bail arm (thus alfordingadvantageous structural simplicity), enable the bail to be moved througha plurality of motion paths as described and in particular to approachthe operating position from the clearance position along an upward andrearward path in which the bail rollers continuously engage the platenso as not only to prevent buckling of the work sheet but also positivelyto smooth the work sheet against the platen. This desired direction ofapproach to the operating position is achieved without the snapping orjerking action commonly encountered in moving a conventionalmultiposition paper bail to operating position from the forwardclearance position III of FIG. 2 and occasioned by the provision of apositive detent at the forward clearance position in conventional bails.

It is to be understood that the invention is not limited to the featuresand embodiments hereinabove specifically set forth but may be carriedout in other ways without departure from its spirit.

I claim:

1. In a typewriter, in combination with a platen and frame structurecarrying said platen, a paper bail structure comprising a torque shaftjournalled for rotation about its 'axis in said frame structure inaxially parallel relation to said platen; a pair of torque armsrespectively fixedly secured to said torque shaft adjacent opposite endsof said platen for rotation with said torque shaft providing forward andrearward pivotal movement of said torque taI'mS relative to said platen,at lea-st one of said torque arms having a slot extending in thedirection of pivotal movement of said torque arms, said slot having aforward end and a rearwar end; -a fixed stop member projecting from saidframe structure through said slot in said one torque arm for engagingsaid forward end of said slot to arrest rearward pivotal movement ofsaid torque arms and engaging said rearward end of said slot 7 to arrestforward pivotal movement of said torque arms; a pair of bail armsrespectively pivotally secured to said torque arms for downward andupward pivotal movement relative to said torque arms, that one of saidbail arms which is mounted to said one torque arm having a projectingportion disposed to engage said stop member upon upward pivotal movementof said bail arms to a preselected upward position thereby to arrestupward displacement of said bail arms at said preselected position; abail member secured to and extending between said bail arms in axiallyparallel relation to said platen and disposed to be carried into andaway from engagement with said platen by downward and upward pivotalmovement of said bail arms at all position of said torque arms; andspring means acting between said frame structure and said bail arms forbiasing said bail arms downwardly when said bail arms are in a downwardposition and upwardly when said bail arms are in said preselected upwardposition while biasing said torque arms rearwardly at all positions ofsaid torque arms and said bail arms.

2. In a typewriter, in combination with a platen and frame structurecarrying said platen, a paper bail structure comprising a torque shaftjournalled for rotation about its axis in said frame structurerearwardly of said platen and in axially parallel relation to saidplaten; a pair of torque arms respectively fixedly secured to saidtorque shaft adjacent opposite ends of said platen for rotation withsaid torque shaft providing forward and rearward pivotal movement ofsaid torque arms relative to said platen, said torque arms extendingupwardly from said torque shaft, at least one of said torque arms havinga slot spaced above said torque shaft, said slot extending in thedirection of pivotal movement of said torque arms and having a forwardend and a rearward end; a fixed stop member projecting from said framestructure through said slot in said one torque arm for engaging saidforward end of said slot to arrest rearward pivotal movement of saidtorque arms and engaging said rearward end of said slot to arrestforward pivotal movement of said torque arms; a pair of bail armsrespectively mounted by pivots to the upper ends of said torque arms fordownward and upward pivotal movement relative to said torque arms, saidbail arms extending forwardly from said pivots, and that one of saidbail arms which is mounted to said one torque arm having a portionprojecting rearwardly from the pivot mounting said one bail arm, saidprojecting portion being disposed to rotate downwardly to engage saidstop member upon upward pivotal movement of said bail arms to apreselected upward position thereby to arrest upward displacement ofsaid bail arms at said preselected position; a bail member secured toand extending between the forward ends of said bail arms in axiallyparallel relation to said platen and disposed to be carried into andaway from engagement with said platen by downward and upward pivotalmovement of said bail arms at all positions of said torque arms; and aspring acting between said frame structure and a point on one of saidbail arms eccentric to the pivot mounting said one bail arm to exertcontinuously on said point a force having a net rearward component, forbiasing said bail arms downwardly when said point is in a first range ofpositions corresponding to downward position of said bail arms andupwardly when said point is rotated into a second range of positions byupward pivotal movement of said bail arms while biasing said torque armsrearwardly at all positions of said torque arms and said bail arms.

3. In a typewriter, in combination with a platen and frame structurecarrying said platen, a paper bail structure comprising a torque shaftjournalled for rotation about its axis in said fname structurerearwardly of said platen and in axially parallel relation to saidplaten; a pair of torque arms respectively fixedly secured to saidtorque shaft adjacent opposite ends of said platen for rotation withsaid torque shaft providing forward and rearward pivotal movement ofsaid torque arms relative to said platen, said torque arms extendingupwardly from said torque shaft and having arcuate slots spaced abovesaid torque shaft, said slots extending in the direction of pivotalmovement of said torque arms and each having a forward end and a rearwarend; a fixed rod secured to said frame structure and extending throughsaid slots of said torque arms in axially parallel relation to saidplaten for engaging said forward ends of said slots to arrest rearwardpivotal movement of said torque arms and engaging said rearward ends ofsaid slots to arrest forward pivotal movement of said torque arms; apair of bail arms respectively mounted by pivots to the upper ends ofsaid torque arms for downward and upward pivotal movement relative tosaid torque arms, said bail arms extending forwardly from said pivotsand having portions projecting rearwardly from said pivots, saidrearwardly projecting portions being disposed to rotate downwardly toengage said rod upon upward pivotal movement of said bail arms to apreselected upward position thereby to arrest upward displacement ofsaid bail arms at said preselected position; a bail member secured toand extending between the forward ends of said bail arms in axialparallel relation to said platen and disposed to be carried into andaway from engagement with said platen by downward and upward pivotalmovement of said bail arms at all positions of said torque arms; a firstpin carried by one of said bail arms at a locality eccentric to thepivot mounting said one bail arm; a second pin carried by said framestructure in facing relation to and below said first pin; and a torsionspring having upper and lower arms respectively bearing against saidfirst and second pins, said torsion spring being continuously undercompression between said pins and being disposed to exert continuouslyon said first pin a force having a net rearward component, for biasingsaid bail arms downwardly when said first pin is in a first range ofpositions corresponding to downward position of said bail arms andupwardly when said first pin is rotated into a second range of positionsby upward pivotal movement of said ball arms while biasing said torquearms rearwardly at all positions of said torque arms and said bail arms.

4. In a typewriter, in combination with a platen and frame structurecarrying said platen, paper bail structure comprising a pair of torquearms respectively pivotally secured to said frame structure at pivotpoints adjacent opposite ends of said platen for forward and rearwardpivotal movement relative to said platen; a fixed stop member projectingfrom said frame structure toward one of said torque arms, said onetorque arm having forward and rearward portions engageable with saidstop member for limiting rearward and forward pivotal movement of saidtorque arms relative to said platen to a predetermined range ofpositions; a pair of bail arms respectively pivotally secured to saidtorque arms for downward and upward pivotal movement relative tosaid'torque arms, that one of said bail arms which is mounted to saidone torque arm having a projecting portion disposed to engage said stopmember upon upward pivotal movement of said bail arms to a preselectedupward position thereby to arrest upward displacement of said bail armsat said preselected position; a bail member secured to and extendingbetween said bail arms in axially parallel relation to said platen anddisposed to be carried into and away from engagement with said platen bydownward and upward pivotal movement of said bail arms at all positionsof said torque arms; and a bias spring anchored to said frame structureand to a point on one of said bail arms, providing a bias force that isdirected rearwardly with respect to the line interconnecting said pointon said last-mentioned bail arm and the pivot point of the torque armconnected to said last-mentioned bail arm throughout said predeterminedrange of torque arm positions, for biasing said bail arms downwardlywhen said bail arms are in a downward position and upwardly when saidbail arms are in an upward position while biasing said torque armsrearwardly at all positions of said torque arms and said bail arms.

References Cited UNITED STATES PATENTS Letterman 197-138 10 2,779,4511/1957 Becker 197-13s 2,930,468 3/1960 Israelson 19-7 13s 3,095,0786/1963 Zeamer 197 13s 3,157,266 11/1964 Dollenmiayer 197 13s 5 FOREIGNPATENTS 570,275 2/1933 Germany.

ROBERT E. PULFREY, Primary Examiner.

10 E. T. WRIGHT, Assistant Examiner.

1. IN A TYPEWRITER, IN COMBINATION WITH A PLATEN AND FRAME STRUCTURECARRYING SAID PLATEN, A PAPER BAIL STRUCTURE COMPRISING A TORQUE SHAFTJOURNALLED FOR ROTATION ABOUT ITS AXIS IN SAID FRAME STRUCTURE INAXIALLY PARALLEL RELATION TO SAID PLATEN; A PAIR OF TORQUE ARMSRESPECTIVELY FIXEDLY SECURED TO SAID TORQUE SHAFT ADJACENT OPPOSITE ENDSOF SAID PLATEN FOR ROTATION WITH SAID TORQUE SHAFT PROVIDING FORWARD ANDREARWARD PIVOTAL MOVEMENT OF SAID TORQUE ARMS RELATIVE TO SAID PLATEN,AT LEAST ONE OF SAID TORQUE ARMS HAVING A SLOT EXTENDING IN THEDIRECTION OF PIVOTAL MOVEMENT OF SAID TORQUE ARMS, SAID SLOT HAVING AFORWARD END AND A REARWARD END; A FIXED STOP MEMBER PROJECTING FROM SAIDFRAME STRUCTURE THROUGH SAID SLOT IN SAID ONE TORQUE ARM FOR ENGAGINGSAID FORWARD END OF SAID SLOT TO ARREST REARWARD PIVOTAL MOVEMENT OFSAID TORQUE ARMS AND ENGAGING SAID REARWARD END OF SAID SLOT TO ARRESTFORWARD PIVOTAL MOVEMENT OF SAID TORQUE ARMS; A PAIR OF BAIL ARMSRESPECTIVELY PIVOTALLY SECURED TO SAID TORQUE ARMS FOR DOWNWARD ANDUPWARD PIVOTAL MOVEMENT RELATIVE TO SAID TORQUE ARMS, THAT ONE OF SAIDBAIL ARMS WHICH IS MOUNTED TO SAID ONE TORQUE ARM HAVING A PROJECTINGPORTION DISPOSED TO ENGAGE SAID STOP MEMBER UPON UPWARD PIVOTAL MOVEMENTOF SAID BAILS ARMS TO A PRESEJECTED UPWARD POSITION THEREBY TO ARRESTUPWARD DISPLACEMENT OF SAID BAIL ARMS AT SAID PRESELECTED POSITION; ABAIL MEMBER SECURED TO AND EXTENDING BETWEEN SAID BAIL ARMS IS AXIALLYPARALLEL RELATION TO SAID ENGAGEMENT WITH SAID BE CARRIED INTO AND AWAYFROM ENGAGEMENT WITH SAID PLATEN BY DOWNWARD AND UPWARD PIVOTAL MOVEMENTOF SAID BAIL ARMS AT ALL POSITIONS OF SAID TORQUE ARMS; AND SPRING MEANSACTING BETWEEN SAID FRAME STRUCTURE AND SAID BAIL ARMS FOR BIASING SAIDBAIL ARMS DOWNWARNDLY WHEN SAID BAIL ARMS ARE IN A DOWNWARD POSITION ANDUPWARDLY WHEN SAID BAIL ARMS ARE IN SAID PRESELECTED UPWARD POSITIONWHILE BIASING SAID TORQUE ARMS REARWARDLY AT ALL POSITIONS OF SAIDTORQUE ARMS AND SAID BAIL ARMS.